The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Existing Delay Tolerant Networking (DTN) software overlay functions operate in the user mode space of a computing operating system (OS) and are suitable for moderate speed networks, typically on the order of 10 s of Mb/s. The DTN framework and protocol provides reliable end-to-end communications in the face of network partitioning or intermittent disruption, for example when a contemporaneous end-to-end path between a source and a destination does not exist. Traditional Internet protocols do not handle these situations well at the application, transport or network layers, resulting in either extremely low throughput or a complete inability to move data. DTN provides custody-based reliability for end-to-end communications among heterogeneous environments via an application layer overlay network that can run on top of an Internet protocol or other protocols. However, since DTN operates as a software overlay networking layer in the user mode space of the OS, it will not fully serve the disruption mitigation requirements of high speed network systems.
Furthermore, invoking DTN, since it is a software overlay function, requires it to operate in the red (i.e., plain-text) side of a cryptographically partitioned network. This is necessary to allow the DTN daemon to perform the custodial transfer of DTN bundles on a hop-by-hop basis from one node to another along the DTN route. High speed link outages, even for short durations (e.g., milliseconds), can result in significant loss of data. The significant loss of data can potentially cause upper layer transport protocols such as TCP/IP to “back-off”. By “back-off”, it will be understood that TCP/IP utilizes a congestion control mechanism to ensure that the source does not transmit TCP/IP packets at a rate beyond what can be sustained on an end-to-end basis. Therefore, source node TCP/IP slowly ramps up the packet transmission rate up to the limit that can be sustained on an end-to-end basis. Source TCP/IP determines the limit based on the timely receipt of the acknowledgement for transmitted packets from the destination node. However, the TCP/IP protocol cannot discern between congestion and loss of packets. Thus, any loss of packets is interpreted as congestion in the network. When the source node TCP/IP does not receive acknowledgements for transmitted packets from the destination node it immediately ramps down the TCP/IP packet transmission rate by half. So the congestion control mechanism of TCP/IP ramps up the rate in single steps up to the objective rate, but when it assumes that the network is congested (which could in fact also be due to packet losses), it will reduce the current transmission rate by 50%. This saw tooth behavior of source node TCP/IP is what is known as “backoff”.
One can see that even a minor disruption resulting in packet loss will cause the source node TCP/IP to backoff resulting in poor network utilization. The process by which the source node TCP/IP slowly ramps up the transmission rate is enabled by what is known as a “slow start” algorithm. When the source node TCP/IP presumes congestions, which could be due to packet loss, it will go into slow start mode resulting in poor network utilization (even with a small packet loss.), causing overall network utilization to significantly deteriorate and adversely impacting the overall completion rates for end-to-end data transmissions.
Quality of Service (QoS) provisioning can be used for data classification on the red side of a node. However, assigning preferential forwarding behavior for data generated by DTN enabled applications, and being transmitted on the black (i.e., cipher-text) high speed side of the node, is difficult to ensure. This is because following the encryption of the packets from various applications on the red (plain-text) side, one cannot discern the red side source or destination applications from the packets on the black (cipher-text) side. This is particularly so when the network is suffering from intermittent link outages.